My infertility is no longer totally unexplained, its now just somewhat unexplained.

Sidious, the dark lord of the cyst turned out to be an endometrioma, and there were some other bits of endometriosis hanging out in my insides. For those who don't know endometriosis is essentially a condition where bits of uterine lining tissue grow outside the uterus. This leads to infertility, not to mention a non-trivial amount of discomfort during your period. So there you have it, my infertility seems to have been caused by endometriosis.

Of course you might ask, 'Just how does endometriosis cause infertility'. In fact I did ask Yoda. His answer: "I wish I knew." That is the catch, no one know exactly why endometriosis causes infertility, just that it does. Yoda went on to explain further, and I shall include bits of his explanation with my own thoughts on the matter.

Now it seems obvious to me that having a 4.8 cm long bit of uterine lining tissue hanging out in your left ovary where it has no business being is not a good thing. Our good friend Sidious, or as the pathology folks call him "part A", was undoutedly thwarting me, but how exactly was he using his evil genius to thwart me? The first theory that Yoda explained was that when its time for your period the endometrioma emit some sort of chemical that interferes with implantation, thereby flushing perfectly good embryos. The catch to this theory is that they have not yet found any such chemical. Another possible mechanism is that the endometriosis interferes with with either the egg getting sucked into the fallopian tubes or it passing through. Yoda said that they'd tried testing this theory with dye and starchballs and such, but alas no of the test correlated at all well to whether or not women got pregnant, so they were pretty much useless. So its still a mystery as to what exactly is going on.

One of the things I love about Yoda is his willingness to get technical with me. If I ask a technical question, he gives me a technical answer. One of the things that Yoda brought up to support his assertions that I have a much better chance of conceiving now was a study. Its called the Endocan study. (I googled it later, couldn't find the study itself, but everything I did find backs Yoda up.) The study was done of women across Canada who had mild endometriosis. They all had surgery, but in half of them the endo was removed, and in half it was just observed and left in. The women who had their endo removed were 50% more likely to conceived than the women who had not had their endo removed. The obvious conclusion is that having the endo out boosts my chances to conceive quite a bit.

So there you have it. I have an explanation and a solution, but the explanation itself could use some explaining

If I had to make up an explanation from scratch, I'd speculate that uterine lining is supposed to be good at sucking up eggs. That's what it's for, right? So it seems like it could suck up early eggs instead of late eggs if it's on the outside nearby.

Well, my wild speculation involves sucking up pre-fertilized eggs before they get to the Fallopian tubes. I don't think the sperm get out of the Fallopian tubes. But I also don't know what happens to unfertilized eggs in the normal course of things, if they stick in the uterine lining or just head out all lonely-like.

Well, firstfrost's theory sounds good, and I expect its a more descriptive version of what Yoda was talking about when he mentioned the endo interfering with the eggs getting swept into the fallopian tubes. That would not lead to ectopics, though, because the egee never gets to the tube if that happens.

On the other hand, women with endometriosis are at higher risk for ectopic pregnacies. The endo can lead to tubal scarring, which can lead to the embryo getting stuck in the tube and growing there instead of making it to the uterus. Ectopic pregnacies suck.

It's a lot shorter than I was expecting. I expect papers to be 60 pages, not 6.

Note: they only studied "mild or minimal" endometriosis. Apparently it was already common knowledge that for women with more advanced endo, surgery improved fertility. The question was whether it's worth doing surgery to go in and get it when it's not so bad, espeically when there are gonadotropin agonists you can take instead.

It's not unique to this study, but this is in the class of medical studies that can't be done double-blind, and not even single-blind. The doctor knows whether s/he did the surgery, and it's generally considered polite to let the patient know if you've done surgery on them. How this affected the patient behavior isn't discussed (maybe the women who had the surgery became more optimistic, and had sex three times a day). Also note that the doctors who did the study do laparoscopic surgery for a living, so they could reinforce any extra optimism the treatment group developed.

While it couldn't very well be double blind, some of the websites I previously found referring to the study said it was single blind. The study itself criticizes previous studies for not being blinded, which tends to support this.

The reason it's possible in this case is because surgery is already the normal way of getting a definitive diagnosis of endometriosis, even if nothing is removed. In fact, I was under the impression that Elizabeth was going in for diagnostic surgery only. Since the patient is under general anaesthesia, she doesn't know whether the surgeon removed the endometriosis after looking around.

There's a lot of other interesting stuff packed into those six pages. Thanks again for finding it for us!

I admit I was kind of confused about the blindedness. I figure that ethics rules for human experimentation would require that you tell someone whether you performed a given surgery on them (i.e., actually took some of you out, rather than just cut you open and poked around). Maybe I'm wrong, and maybe the rules in Canada are different from what I'm familiar with.

Even if you'd agreed to be in a study, don't you think it would be disturbing if Yoda refused to tell you whether he'd actually done the removal or not?